Accelerated data recovery in a storage system

ABSTRACT

One embodiment provides a storage system. The storage system includes storage system control logic to identify at least one target storage device in response to detection of a failed storage device, request a state of a target device logical block address (LBA) from each of the at least one target storage device, and read data associated with a mapped device LBA from each target storage device and write the data to at least one replacement storage device. Another embodiment provides a storage device. The storage device includes device control logic to determine a state of a target device logical block address (LBA) in response to a request; a host interface to provide a reply to the request, the reply including a state indicator related to the state of the target device LBA; a map table including a plurality of device LBAs and respective state indicators; and non-volatile memory (NVM) including data related to at least one mapped LBA.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. patent applicationSer. No. 14/568,417 filed Dec. 12, 2014, the entire disclosure of whichis incorporated herein by reference.

FIELD

The present disclosure relates to accelerated data recovery, inparticular to, accelerated data recovery in a storage system.

BACKGROUND

RAID (redundant array of independent (inexpensive) disks) systemsinclude a plurality of storage devices configured to provide improvedperformance and/or fault tolerance relative to a single storage device.In redundant storage systems (e.g., RAID systems above level 0), one ormore copies of data and/or parity information may be stored on aplurality of storage devices. Data stored on a failed storage device maybe recovered from the cop(ies) and/or related parity information andstored on a replacement storage device. Such recovery and storageoperations are known as “rebuilding”. Generally, rebuilding a failedstorage device includes writing an entire address space of the failedstorage device from the cop(ies) to the replacement storage device. Asstorage capacities of storage devices increase, the time duration ofrebuild operations for a failed storage device also increases.

BRIEF DESCRIPTION OF DRAWINGS

Features and advantages of the claimed subject matter will be apparentfrom the following detailed description of embodiments consistenttherewith, which description should be considered with reference to theaccompanying drawings, wherein:

FIG. 1 illustrates a functional block diagram of a system consistentwith various embodiments of the present disclosure;

FIG. 2 is a flowchart of accelerated data recovery operations accordingto various embodiments of the present disclosure;

FIG. 3 is a flowchart of storage device operations according to variousembodiments of the present disclosure; and

FIGS. 4A and 4B illustrate one example of accelerated data recovery in aRAID (redundant array of independent (inexpensive) disks) level 1system.

Although the following Detailed Description will proceed with referencebeing made to illustrative embodiments, many alternatives,modifications, and variations thereof will be apparent to those skilledin the art.

DETAILED DESCRIPTION

Generally, this disclosure relates to accelerated recovery methods (andsystems) in a storage system. The storage system may include a pluralityof storage devices configured to provide fault tolerance. In response toa failure of a storage device, the methods (and systems) are configuredquery one or more other storage device(s) to identify mapped logicalblock addresses (LBAs) related to the failed storage device.

The methods and systems are further configured to provide an acceleratedrebuild of a replacement storage device by reading and writing (i.e.,copying) data associated with mapped LBA(s). In other words, rather thancopying contents of all storage elements associated with the failedstorage device to the replacement storage device, the contents ofstorage elements associated with mapped LBA(s) may be copied. Thus, atime duration associated with rebuilding the failed storage device maybe reduced relative to copying an entire span (i.e., range of LBAsavailable for user data) of a storage device. By querying the storagedevice(s), i.e., by requesting state(s) of device LBA(s) from thestorage device(s), such rebuilds may be performed independent ofexistence and/or type of file system that may be resident on a hostcomputing device coupled to the storage system. Such rebuilds may alsobe performed independent of partitioning of the storage system by, e.g.,an operating system (OS).

As used herein, an unmapped device LBA is a storage device LBA that hasnot been written to or has been subject to a trim command (TRIM) and hasnot been written to since the TRIM, as described herein. A mapped deviceLBA is a storage device LBA that has been written to and has not beensubject to a TRIM since being written to. Mapped and unmapped, asapplied to a device LBA, correspond to respective states of the deviceLBA. Mapping within a storage device is configured to relate a deviceLBA to a physical block address (PBA) associated with a physical storagemedium included in the storage device. Mapping may also be used torelate a host LBA to a device LBA.

FIG. 1 illustrates a functional block diagram of a system 100 consistentwith various embodiments of the present disclosure. System 100 includesa computing device 102 and a storage system 104. The storage system 104includes storage system control logic 106 and one or more storagedevice(s) 110 a, 110 b, . . . , 110 m. System 100 may include one ormore peripheral device(s) 140 coupled to computing device 102. Computingdevice 102 may include, but is not limited to, a server, a workstationcomputer, a desktop computer, a laptop computer, a tablet computer(e.g., iPad®, GalaxyTab® and the like), an ultraportable computer, anultramobile computer, a netbook computer and/or a subnotebook computer;a mobile telephone including, but not limited to a smart phone, (e.g.,iPhone®, Android®-based phone, Blackberry®, Symbian®-based phone,Palm®-based phone, etc.) and/or a feature phone.

Computing device 102 includes a processor 120, a chipset 122 and amemory 126. Processor 120 may include one or more processing unit(s)(e.g., processor(s) and/or core(s)) and is configured to performoperations associated with computing device 102. Chipset 122 may includea storage device interface 124. Chipset 122 and/or storage deviceinterface 124 may be configured to couple processor 120 to storagesystem 104, storage system control logic 106 and/or peripheral device(s)140. Storage device interface 124 may be configured to communicate withstorage system 104, storage system control logic 106 and/or peripheraldevice(s) 140 via one or more interface and/or interconnect protocols,e.g., PCIe® (Peripheral Component Interconnect Express), SAS (SerialAttached SCSI (Small Computer System Interface)), ATA (AdvancedTechnology Attachment), SATA (Serial ATA), NVMe (Non-Volatile MemoryHost Controller Interface Express), etc. Peripheral device(s) 140 mayinclude, for example, user interface device(s) including a display, atouch-screen display, printer, keypad, keyboard, etc., communicationlogic, wired and/or wireless, other storage device(s) including harddisk drives, solid-state drives, removable storage media, etc.

Memory 126 may include cache and/or random access memory. Memory 126 isconfigured to store an OS 130 and one or more application(s) 134. Theapplication(s) 134 may be configured to initiate memory accessoperations related to storage system 104. OS 130 may include a filesystem 132. File system 132 is configured to manage file storage and/orretrieval for computing device 102. For example, file system 132 may beincluded in a storage stack that includes one or more of the interfaceand/or interconnect protocols, storage system control logic 106 andstorage system 104 (e.g., storage device 110 a and/or device controllogic 150, as described herein).

Storage system 104 includes one or more storage device(s) 110 a, 110 b,. . . , 110 m. For example, the storage devices 110 a, 110 b, . . . ,110 m may include, but are not limited to, solid state drives (SSDs),hard disk drives (HDD), etc. Each storage device, e.g., storage device110 a, includes device control logic 150, a host interface 152, a cachememory 154, a non-volatile memory (NVM) 156 and a map table 158. Cachememory 154 may include non-volatile memory, as described herein, orvolatile memory, e.g., dynamic random access memory (DRAM), synchronousDRAM (SDRAM), etc. Device control logic 150 is configured to manageoperations of storage device 110 a. Device control logic 150 isconfigured to write data to and read data from NVM 156. NVM 156 isconfigured to store user data, parity information and/or NVM operationalinformation. NVM operational information may include logic associatedwith operation of storage device 110 a and/or metadata. NVM 156 includesa plurality of storage elements that may be organized in pages and/orblocks. Block(s) of storage elements in NVM 156 may be identified byphysical block address(es) (PBA(s)). Data received from computing device102 and/or storage system control logic 106 may be identified by deviceLBA(s). Device control logic 150 may be configured to relate each deviceLBA to a respective PBA and store the result in map table 158. Map table158 may further include a state indicator associated with each deviceLBA. Map table 158 may be resident in NVM 156 and/or cache 154. Thestate indicator may have two values that correspond to a mapped deviceLBA (e.g., logic one) and an unmapped device LBA (e.g., logic zero),respectively. For example, device control logic 150 may be configured toset the associated state indicator to logic one when a respective deviceLBA is written to (i.e., mapped) and reset the associated stateindicator from logic one to logic zero when a previously mapped deviceLBA becomes unmapped. Thus, map table 158 may be utilized by devicecontrol logic 150 to identify a state of each device LBA(s), asdescribed herein.

Storage device(s) 110 a, 110 b, . . . , 110 m may correspond to harddisk drive(s) (HDD(s)) and/or solid state drive(s) (SSD(s)). For storagedevices that are HDDs, NVM 156 may include ferromagnetic material. Forstorage devices that are SSDs, NVM 156 may include, but is not limitedto, magnetoresistive random access memory (MRAM), phase change memory(PCM, PRAM), three dimensional crosspoint memory, resistive memory,ferroelectric memory (F-RAM, FeRAM), spin-transfer torque memory (STT),thermal assisted switching memory (TAS), millipede memory, floatingjunction gate memory (FJG RAM), magnetic tunnel junction (MTJ) memory,electrochemical cells (ECM) memory, binary oxide filament cell memory,interfacial switching memory, battery-backed RAM, NAND flash memory,etc.

Host interface 152 is configured to receive commands and/or data fromcomputing device 102 and/or storage system control logic 106 and totransmit responses (i.e., replies) and/or data to computing device 102and/or storage system control logic 106. Host interface 152 may beconfigured to couple storage device 110 a to storage system controllogic 106 and/or host device 102. Host interface 152 may comply and/orbe compatible with one or more interface and/or interconnectprotocol(s), as described herein. Host interface 152 may be furtherconfigured to decode received commands and/or data and to provide thedecoded commands and/or data to device control logic 150. Host interface152 may be further configured to encode data and/or response(s) fromdevice control logic 150 to a format (and/or syntax) that compliesand/or is compatible with the interface and/or interconnect protocol(s).Cache 154 is configured to store commands and/or data. Commands and/ordata may be stored in cache 154 prior to decoding and/or prior toencoding. Received data, e.g., data received from computing device 102,may be stored in cache 154 prior to being written to NVM 156. Thus, hostinterface 152 may provide an interface, interconnect and/orcommunication between storage device 110 a and computing device 102and/or storage system control logic 106.

Storage system control logic 106 may be resident in storage system 104,may be coupled between computing device 102 and storage system 104and/or may be resident in computing device 102. Storage system controllogic 106 is configured to manage memory access operations (e.g., readand/or write operations) between computing device 102, storage system104 (and storage devices 110 a, 110 b, . . . , 110 m). Storage systemcontrol logic 106 is configured to abstract storage devices 110 a, 110b, . . . , 110 m to computing device 102. For example, storage system104 may correspond to a RAID system and storage system control logic 106may then correspond to a RAID controller.

Storage system control logic 106 is configured to receive read and/orwrite commands and associated host LBA(s) from computing device 102(e.g., from file system 132) and to determine, select and/or identifyappropriate storage device(s) 110 a, 110 b, . . . , and/or 110 m based,at least in part, on the host LBA(s). Storage system control logic 106may be configured to map each host LBA to one or more respective deviceLBA(s). In a redundant storage system, one host LBA may be mapped todevice LBAs associated with more than one storage device. Storage systemcontrol logic 106 is further configured to receive user data associatedwith the host LBA(s). Storage system control logic 106 may receive readdata from one or more storage device(s) 110 a, 110 b, . . . , 110 m andprovide the read data to computing device 102.

In write operations, storage system control logic 106 may be configuredto determine and/or select appropriate storage device(s) 110 a, 110 b, .. . , and/or 110 m based, at least in part, on the host LBA(s). Forexample, storage system control logic 106 may be configured todistribute user data associated with a write command across a pluralityof the storage devices 110 a and 110 b, . . . , and/or 110 m in order toprovide redundancy and/or relatively better performance compared to astorage system that includes a single storage device. Thus, in thisexample, storage system control logic 106 may be configured to select aplurality of storage devices 110 a and 110 b, . . . , and/or 110 m toassociate with subsets of received host LBA(s). Storage system controllogic 106 may be further configured to relate each subset of host LBA(s)to a respective plurality of device LBA(s) for each storage device.Storage system control logic 106 may be further configured to determineparity information, e.g., a checksum, based, at least in part, on datato be written, and to store the parity information to device LBA(s) ofone or more of the storage device(s) 110 a, 110 b, . . . , and/or 110 m.In another example, storage system control logic 106 may be configuredto select one storage device, e.g., storage device 110 a, to associatewith the host LBAs and to receive the user data. Storage system controllogic 106 may be further configured to determine parity informationbased, at least in part, on data to be written, and to store the parityinformation to another of the storage devices 110 b, . . . , or 110 m.In both examples, storage system control logic 106 may be configured toprovide write command(s), data (e.g., user data and/or parityinformation) and associated device LBA(s) to selected storage device(s)110 a, 110 b, . . . , and/or 110 m.

In read operations, storage system control logic 106 is configured toidentify appropriate storage device(s) 110 a, 110 b, . . . , and/or 110m and to provide read command(s) and associated device LBA(s) toidentified storage device(s) 110 a, 110 b, . . . , and/or 110 m based,at least in part, on host LBA(s). Storage system control logic 106 maybe further configured to receive the read user data from the identifiedstorage device(s) 110 a, 110 b, . . . , and/or 110 m and to provide theread data to computing device 102. Storage system control logic 106 maybe configured to verify that read data is not corrupted based, at leastin part, on parity and/or redundant information associated with the readdata. Storage system control logic 106 may be further configured tocorrect corrupted data, if possible, based, at least in part, on theparity and/or redundant information.

Storage system control logic 106 is configured to detect failure of oneor more of storage devices 110 a, 110 b, . . . , and/or 110 m. Storagesystem control logic 106 may be further configured to initiate rebuildoperations in response to a detected failure. Storage system controllogic 106 may be configured to communicate the failure to computingdevice 102. Computing device 102 and/or OS 130 may be configured tonotify, e.g., a user via peripheral device(s) 140, that a storage devicehas failed. The notice is configured to prompt the user to replace thefailed storage device with a replacement storage device. For example,storage system control logic 106 may be configured to receive anindication from a user via computing device 102 and/or peripheraldevice(s) 140 that a replacement storage device has been coupled tostorage system control logic 106. In another example, storage systemcontrol logic 106 may be configured to detect that a replacement storagedevice has been coupled to storage system control logic 106 in place ofthe failed storage device. In another example, storage system 104 mayinclude a replacement storage device configured to be utilized if astorage device fails. The replacement storage device may exist instorage system 104 prior to a failure of a storage device and/or may beadded by the user after the failure is detected.

Generally, when rebuild operations are initiated, the failed storagedevice may be storing less than a maximum storage capacity of the failedstorage device. In other words, fewer device LBA(s) than the span (i.e.,the range of device LBAs that may store user data) of the failed storagedevice may be mapped. Rebuild operations may be accelerated by buildingmapped portions of the failed storage device rather than the entire spanof the failed storage device.

In an embodiment, storage system control logic 106 may be configured torequest respective state(s) of target device LBA(s) from each storagedevice 110 a, 110 b, . . . , and/or 110 m (“target storage device(s)”)that may have mapped device LBAs related to the failed storage device.Storage system control logic 106 may be configured to identify thetarget storage device(s) based, at least in part, on a configuration ofstorage system 104. Storage system control logic 106 may be furtherconfigured to identify target device LBA(s) based, at least in part, onthe configuration of storage system 104. For example, in a mirroredconfiguration, one target storage device may include mapped LBA(s)related to the failed storage device. In another example, in aconfiguration that implements striping (e.g., RAID), a plurality ofstorage devices may include mapped device LBAs related to the failedstorage device. The plurality of storage devices may be included in astorage pool. Storage system control logic 106 may be configured toidentify the plurality of target storage devices based, at least inpart, on the storage pool.

Storage system control logic 106 may be configured to identify thetarget storage device(s) and request the state(s) of target deviceLBA(s) in response to an indication that a storage device has failed.For example, storage system 104 may be configured to provide redundancyby mirroring stored data on a first storage device and a second storagedevice (e.g., RAID 1). Storage system control logic 106 may then beconfigured to request respective state(s) of target device LBA(s) fromthe second storage device if the first storage device fails. In thisexample, rebuild operations may then include copying data associatedwith the mapped device LBA(s) from the target storage device (i.e., thesecond storage device) to the replacement storage device.

In another example, storage system 104 may be configured to providefault tolerance by “striping” blocks of data across a plurality ofstorage devices (i.e., storage pool) and distributing parity informationacross the plurality of storage devices (e.g., RAID 5). A stripe of dataincludes segments of logically sequential data that are distributedacross a plurality of storage devices, i.e., a storage pool. Storagesystem control logic 106 may be configured to identify the plurality ofstorage devices in the storage pool. Storage system control logic 106may then be configured to request respective state(s) of target deviceLBA(s) from each of the plurality of storage devices (except the failedstorage device) in the storage pool. The state(s) of target deviceLBA(s) may be requested for a stripe of data. Whether to read and writethe target device LBAs in the stripe may then be determined for theplurality of target storage devices in the storage pool. In thisexample, rebuild operations may include determining and/or verifyingvalues of stored data based, at least in part, on the parityinformation. Stripes of unmapped target device LBAs may not be read norwritten.

In some embodiments, file system 132 may be configured to provide a trim(TRIM) command and associated host LBA(s) 162 to storage system controllogic 106. TRIM is configured to communicate host LBAs to storage system104 that have been unmapped by the file system 132. For example, hostLBAs may be unmapped in response to a permanent deletion of a file,emptying a “recycle bin” and/or performing a “quick format”, e.g., in aMicrosoft® Windows® OS. TRIM is configured to optimize garbagecollection and erase operations in SSDs that erase blocks of storageelements prior to writing new data to the storage elements.

In these embodiments, storage system control logic 106 may be configuredto send a TRIM request 160 to computing device 102 in response to astorage device failure. The TRIM request 160 is configured to triggertransmission of a TRIM command and associated host LBA(s) 162 from filesystem 132 to storage system 104. The TRIM command may comply and/or becompatible with one or more interface and/or interconnect protocols, asdescribed herein. For example, the TRIM command may correspond to an ATADATA SET MANAGEMENT command, a SCSI (and/or SAS) UNMAP command and/or anNVMe DEALLOCATE command, as described herein. Storage system controllogic 106 may receive the TRIM command and associated host LBAs 162 andmay provide a corresponding TRIM command and associated device LBAs 164to the target storage device(s). For example, a host interface of eachtarget storage device, e.g., host interface 152 of storage device 110 a,may be configured to receive command(s), data and/or device LBA(s)formatted according to a respective interface and/or interconnectprotocol and to provide the command(s), data and/or device LBA(s) to,e.g., device control logic 150. Device control logic of each targetstorage device, e.g., device control logic 150, may then be configuredto unmap the device LBA(s) that correspond to received TRIM command.Thus, in response to the TRIM command the target storage device(s) mayhave a most up-to-date mapping (and unmapping) of device LBA(s).

Storage system control logic 106 is configured to send a request forstate of target device LBA(s) command (LBA state request command) 166 toeach target storage device, e.g., storage device 110 a, associated withthe failed storage device. In an embodiment, the LBA state requestcommand may include one or more target device LBA(s). In anotherembodiment, the LBA state request command may request a listing ofmapped device LBA(s) and/or a listing of unmapped device LBA(s). Storagesystem control logic 106 may send the LBA state request command 166 inresponse to a failure of a storage device, e.g., storage device 110 b.For example, the LBA state request command 166 may be sent without firstsending the TRIM request command 160. In another example, the LBA staterequest command 166 may be sent after sending the TRIM request command160 and/or after receiving the TRIM command and associated host LBA(s)162.

The LBA state request command 166 may correspond to and/or be compatiblewith one or more of the interface and/or interconnect protocols, asdescribed herein. In some embodiments, the LBA state request command 166may have an associated syntax that is specific to a selected storagedevice, e.g., storage device 110 a. A specific syntax may be configuredto provide a level of security by limiting use of the command toselected storage devices (e.g., vendor-specific). The specific syntaxmay be further configured to provide a vendor-specific command. Forexample, a vendor-specific command may simplify a command structureand/or facilitate device testing.

Each target storage device, e.g., storage device 110 a, may beconfigured to provide a response 168 (i.e., reply 168) to storage systemcontrol logic 106 that includes state indicator(s) corresponding to therequested state(s) of the target device LBA(s). The repl(ies) 168 maycomply and/or be compatible with one or more interface and/orinterconnect protocols. For example, host interface 152 may beconfigured to receive the LBA state request command 166, to decode thecommand 166 and to provide the decoded request to device control logic150. Device control logic 150 may be configured to identify the state(s)of target device LBA(s) based, at least in part, on map table 158. Forexample, map table 158 may relate device LBA(s) to NVM 156 PBA(s) andmay further include a state indicator, e.g., a flag, that corresponds toa state of an associated device LBA. For example, the flag may be a bitand may have a value of one (e.g., TRUE) for a target device LBA that ismapped and a value of zero (e.g., FALSE) for a target device LBA that isunmapped. Device control logic 150 may be configured to read map table158 and the associated indicators to identify the state(s) of targetdevice LBA(s). Device control logic 150 may then be configured toprovide the state(s) to host interface 152. Host interface 152 may thengenerate the reply 168 that includes the state(s) of target deviceLBA(s) and to transmit the response to storage system control logic 106.Responses that include the states of a plurality of target device LBA(s)may be configured to relate each state indicator to its respectivetarget device LBA. The reply 168 may comply and/or be compatible withone or more interface and/or interconnect protocols, as describedherein.

In an embodiment, storage system control logic 106 may be configured toinclude a target device LBA with the request for mapped and/or unmappeddevice LBA(s) command 166. In this embodiment, each target storagedevice is configured to determine a state of the target device LBA andto provide the resulting state indicator to storage system control logic106 in reply 168. For example, the LBA state request command 166 thatincludes the target device LBA may be sent during rebuild, e.g., priorto building each target device LBA.

In another embodiment, storage system control logic 106 may beconfigured to include a range of target device LBAs with the LBA staterequest command 166. In this embodiment, each target storage device maybe configured to determine a respective state of each device LBAincluded in the range of target device LBA(s) and to provide theresulting state indicator(s) to storage system control logic 106 inreply 168. For example, the LBA state request command 166 that includesthe range of target device LBAs may be sent prior to and/or duringrebuild, e.g., prior to building the target device LBAs.

In another embodiment, storage system control logic 106 may beconfigured to request a listing of mapped device LBA(s) and/or a listingof unmapped device LBA(s). In this embodiment, each target storagedevice may be configured to provide device LBA(s) and associated stateindicators from map table 158 in their respective replies 168. Forexample, the LBA state request command 166 that includes the request forthe listing(s) may be sent prior to rebuild.

Thus, the storage system control logic 106 may request state(s) oftarget device LBA(s) from target storage device(s) in response todetection of a failed storage device. The target storage device(s) maythen provide the state indicator(s) of the target device LBA(s) to thestorage system control logic 106 in response to the request. The storagesystem control logic 106 may then be configured to identify a respectivestate of each target device LBA. For example, storage system controllogic 106 may be configured to perform a logical OR operation (e.g.,exclusive OR (XOR)) of the state indicator(s) and a test value toidentify the respective state(s).

Storage system control logic 106 may then be configured to build areplacement storage device, e.g., storage device 110 a, configured toreplace the failed storage device, e.g., storage device 110 b. Forexample, storage system control logic 106 may be configured to send aread command that includes mapped device LBA(s) to the target storagedevice(s) and to write the read data to corresponding device LBA(s) ofthe replacement storage device 110 a. Unmapped device LBA(s) may not beread and may not be written. The data may include user data and/orparity information, as described herein. Storage system control logic106 may be further configured to update parity information associatedwith the replacement storage device 110 a. Thus, a rebuild of the failedstorage device 110 b may be accelerated as described herein by readingand writing mapped device LBA(s) and not reading and not writingcontents of unmapped device LBA(s). The rebuild may be performedindependent of a file system, e.g., file system 130, file structureand/or partitioning related to computing device 102.

FIG. 2 is a flowchart 200 of accelerated data recovery operationsaccording to various embodiments of the present disclosure. Inparticular, flowchart 200 illustrates acquiring state(s) of targetdevice LBA(s) associated with a failed storage device and building areplacement storage device by writing the contents of the mapped deviceLBA(s) to the replacement storage device. The operations may beperformed, for example, by storage system control logic 106 of FIG. 1.

Operations of this embodiment may begin with a storage device failure202. In some embodiments, a TRIM command may be requested at operation204. For example, the TRIM command may be requested from a file systemincluded in a computing device, e.g., file system 132 of computingdevice 102. Target storage device(s) may be identified at operation 206.Target storage device(s) may be storing data related to the failedstorage device. For example, in a mirrored system, one failed storagedevice may correspond to one target storage device. In another example,in a striped system, one failed storage device may be related to aplurality of target storage devices. Target device LBA(s) may beidentified at operation 208. A respective state of each identifiedtarget device LBA may be requested at operation 210. For example, therespective state(s) may be requested from target storage device(s) thatinclude data related to data stored on the failed storage device.Requested state indicator(s) may be received at operation 212. Dataassociated with mapped device LBA(s) may be read from the target storagedevice(s) and written to at least one replacement storage device atoperation 214. For example, data associated with the mapped deviceLBA(s) may include user data and/or parity information. Program flow maythen continue at operation 216.

Thus, a rebuild of a failed storage device may be accelerated by copyingdata associated with mapped device LBA(s) from target storage device(s)(i.e., reading) to the replacement storage device (i.e., writing).Whether a device LBA is mapped or unmapped may be determined based, atleast in part, on LBA state information received from the target storagedevice(s).

FIG. 3 is a flowchart 300 of storage device operations according tovarious embodiments of the present disclosure. In particular, flowchart300 illustrates unmapping device LBA(s) in response to a TRIM commandand providing respective state(s) of target device LBA(s) in response toa request for them. The operations may be performed by a storage device,for example, one or more of storage device(s) 110 a, 110 b, . . . ,and/or 110 m of FIG. 1.

Operations of this embodiment may begin with start 302. In someembodiments, a TRIM command may be received at operation 304. The TRIMcommand is configured to identify device LBA(s) that correspond to hostLBA(s) that have been unmapped by, e.g., a file system. Device LBA(s)associated with the TRIM command may be unmapped at operation 306.Whether operations 304 and 306 are performed may depend on whether anOS, e.g., OS 130, includes a TRIM command.

Operations of this embodiment include receiving a request for state(s)of target device LBA(s) at operation 308. One or more state(s) of targetdevice LBA(s) may be determined in response to the request at operation310. For example, state(s) of target device LBA(s) may be determinedbased, at least in part, on a map table, e.g., map table 158 of FIG. 1.Operation 312 includes providing a reply that includes a respectivestate indicator related to the state of each target device LBA. Forexample, the response may be provided to storage system control logic.Program flow may end at operation 314. Thus, a storage device mayprovide respective state indicator(s) of one or more target deviceLBA(s) in response to a request from, e.g., storage system controllogic.

While the flowcharts of FIGS. 2 and 3 illustrate operations accordingvarious embodiments, it is to be understood that not all of theoperations depicted in FIGS. 2 and/or 3 are necessary for otherembodiments. In addition, it is fully contemplated herein that in otherembodiments of the present disclosure, the operations depicted in FIGS.2 and/or 3, and/or other operations described herein may be combined ina manner not specifically shown in any of the drawings, and suchembodiments may include less or more operations than are illustrated inFIGS. 2 and/or 3. Thus, claims directed to features and/or operationsthat are not exactly shown in one drawing are deemed within the scopeand content of the present disclosure.

FIGS. 4A and 4B illustrate one example of accelerated data recovery in aRAID level 1 (i.e., mirrored) system. FIG. 4A illustrates an example 400of NVM 402, 404 of a RAID 1 that includes two storage devices (Device 0and Device 1) configured to mirror stored data. In other words, the NVM402, 404 of each device is configured to store the same data as the NVM404, 402 of the other device. In both devices, device LBA(s) A1, A2, . .. , AN are mapped and LBA(s) AN+1, . . . , AY are unmapped. In example400, Device 1 has failed. Example 400 further includes a replacementdevice (Device R) that is configured to replace failed Device 1. DeviceR includes NVM 406 that includes device LBA(s) A1, A2, . . . , AY thatare unmapped. In other words the span of NVM 406 is unmapped. A user mayremove failed Device 1 and replace Device 1 with Device R.

FIG. 4B illustrates the example 400′ of FIG. 4A after the failed Device1 has been replaced with Device R. Storage system control logic, e.g.,storage system control logic 106 of FIG. 1, is configured to requeststate(s) of target device LBA(s) from Device 0, for example, by sendinga LBA state request command to Device 0, as described herein. Device 0is configured to receive the request and to transmit respective stateindicator(s) of device LBA(s), A1, A2, . . . , AN (i.e., mapped), to thestorage system control logic in response to receiving the LBA staterequest command, as described herein. The storage system control logicmay then be configured to copy the data associated with mapped deviceLBA(s) A1, A2, . . . , AN from NVM 402 to NVM 406. Device LBA(s) AN+1, .. . , AY of NVM 406 may remain unmapped. Thus, rebuilding a failedstorage device may be accelerated, as described herein, compared tocopying the full span.

Turning again to FIG. 1, OS 130 may be configured to manage system 100resources and control tasks that are run on each respective deviceand/or system, e.g., computing device 102 and/or storage system 104. Forexample, the OS may be implemented using Microsoft® Windows®, HP-UX®,Linux®, or UNIX®, although other operating systems may be used. In someembodiments, the OS 130 may be replaced by a virtual machine monitor (orhypervisor) which may provide a layer of abstraction for underlyinghardware to various operating systems (virtual machines) running on oneor more processing units.

Memory 126 may include one or more of the following types of memory:semiconductor firmware memory, programmable memory, non-volatile memory,read only memory, electrically programmable memory, random accessmemory, flash memory, magnetic disk memory, and/or optical disk memory.Either additionally or alternatively device memory may include otherand/or later-developed types of computer-readable memory.

Embodiments of the operations described herein may be implemented in acomputer-readable storage device having stored thereon instructions thatwhen executed by one or more processors perform the methods. Theprocessor may include, for example, a processing unit and/orprogrammable circuitry. The storage device may include a machinereadable storage device including any type of tangible, non-transitorystorage device, for example, any type of disk including floppy disks,optical disks, compact disk read-only memories (CD-ROMs), compact diskrewritables (CD-RWs), and magneto-optical disks, semiconductor devicessuch as read-only memories (ROMs), random access memories (RAMs) such asdynamic and static RAMs, erasable programmable read-only memories(EPROMs), electrically erasable programmable read-only memories(EEPROMs), flash memories, magnetic or optical cards, or any type ofstorage devices suitable for storing electronic instructions.

As used in any embodiment herein, the term “logic” may refer to an app,software, firmware and/or circuitry configured to perform any of theaforementioned operations. Software may be embodied as a softwarepackage, code, instructions, instruction sets and/or data recorded onnon-transitory computer readable storage medium. Firmware may beembodied as code, instructions or instruction sets and/or data that arehard-coded (e.g., nonvolatile) in memory devices.

“Circuitry”, as used in any embodiment herein, may comprise, forexample, singly or in any combination, hardwired circuitry, programmablecircuitry such as computer processors comprising one or more individualinstruction processing cores, state machine circuitry, and/or firmwarethat stores instructions executed by programmable circuitry. The logicmay, collectively or individually, be embodied as circuitry that formspart of a larger system, for example, an integrated circuit (IC), anapplication-specific integrated circuit (ASIC), a system on-chip (SoC),desktop computers, laptop computers, tablet computers, servers, smartphones, etc.

Computing device 102 and storage system 104 may be configured tocommunicate with each other via one or more interface and/orinterconnect protocols. Storage system control logic 106 and storagedevice(s) 110 a, 110 b, . . . , and/or 110 m may be configured tocommunicate with each other via one or more interface and/orinterconnect protocols.

In one example, the interface and/or interconnect protocol may complyand/or be compatible with PCIe® (Peripheral Component InterconnectExpress) specification, titled: PCI Express® Base Specification,Revision 3.0, released by PCI-SIG® (PCI Special Interest Group),Beaverton, Oreg., November 2010, and/or later versions of thisspecification, for example, version 3.1.

In another example, the interface and/or interconnect protocol maycomply and/or be compatible with SAS (Serial Attached SCSI (SmallComputer System Interface)) standard SAS-3, titled: Serial AttachedSCSI-3 (SAS-3) 2212-D ANSI-approved, published by American NationalStandards Institute (ANSI) InterNational Committee for InformationTechnology Standards (INCITS), November, 2013, and/or later versions ofthis standard.

In another example, the interface and/or interconnect protocol maycomply and/or be compatible with ATA (Advanced Technology Attachment)standard, document number: INCITS 452-2009/AM1-2010, titled: InformationTechnology-AT Attachment 8-ATA/ATAPI Command Set (ATA8-ACS) Amendment 1,published in 2010 by ANSI INCITS, and/or related and/or later versionsof this standard, for example, document number: INCITS 482-2012, titled:Information Technology-ATA/ATAPI Command Set-2 (ACS-2), published in2012, and/or later and/or related versions of this standard.

In another example, the interface and/or interconnect protocol maycomply and/or be compatible with SATA (Serial ATA (Advanced TechnologyAttachment)) specification, titled: Serial ATA Specification, Revision3.2, released August 2013, by SATA International Organization (SATA-IO),Beaverton, Oreg., and/or earlier and/or later versions of thisspecification.

In another example, the interface and/or interconnect protocol maycomply and/or be compatible with NVMe (Non-Volatile Memory HostController Interface Express) specification titled: NVM Express™,Revision 1.2, released Nov. 3, 2014 by NVM Express™ Work Group, and/orearlier and/or later versions of this specification.

In some embodiments, a hardware description language (HDL) may be usedto specify circuit and/or logic implementation(s) for the various logicand/or circuitry described herein. For example, in one embodiment thehardware description language may comply or be compatible with a veryhigh speed integrated circuits (VHSIC) hardware description language(VHDL) that may enable semiconductor fabrication of one or more circuitsand/or logic described herein. The VHDL may comply or be compatible withIEEE Standard 1076-1987, IEEE Standard 1076.2, IEEE1076.1, IEEE Draft3.0 of VHDL-2006, IEEE Draft 4.0 of VHDL-2008 and/or other versions ofthe IEEE VHDL standards and/or other hardware description standards.

Thus, consistent with the teachings of the present disclosure, a systemand method are configured to provide an accelerated rebuild of areplacement storage device by reading and writing (e.g., copying) dataassociated with mapped device LBA(s). In other words, rather thancopying all device LBAs associated with the failed storage device to thereplacement storage device, the data associated with device LBA(s)determined to be mapped may be copied. Thus, a time duration associatedwith rebuilding the failed storage device may be reduced relative tocopying an entire span of a storage device. By requesting state(s) oftarget device LBA(s) from the storage device(s), such rebuilds may beperformed independent of existence and/or type of file system that maybe resident on a host computing device coupled to the storage system.

EXAMPLES

Examples of the present disclosure include subject material such as amethod, means for performing acts of the method, a device, or of anapparatus or computer-readable storage device related to accelerateddata recovery in a storage system, as discussed below.

Example 1

According to this example there is provided a storage system. Thestorage system includes storage system control logic. The storage systemcontrol logic is to identify at least one target storage device inresponse to detection of a failed storage device, request a state of atarget device logical block address (LBA) from each of the at least onetarget storage device, and read data associated with a mapped device LBAfrom each target storage device and write the data to at least onereplacement storage device.

Example 2

This example includes the elements of example 1, wherein the storagesystem control logic is further to request a trim command (TRIM) from acomputing device to be provided to each target storage device.

Example 3

This example includes the elements of example 1, wherein the storagesystem control logic is further to identify each target device LBA.

Example 4

This example includes the elements of example 1, wherein the storagesystem control logic is further to request from each target storagedevice a respective state of each target device LBA of a range of targetdevice LBAs.

Example 5

This example includes the elements of example 1, wherein the storagesystem control logic is further to request a listing of mapped deviceLBAs from each target storage device.

Example 6

This example includes the elements of example 1, wherein the statecorresponds to mapped or unmapped.

Example 7

This example includes the elements according to any one of examples 1through 6, wherein the storage system control logic is to request thestate of each target device LBA at least one of prior to and/or during arebuild of the failed storage device.

Example 8

This example includes the elements according to any one of examples 1through 6, wherein the request includes a respective target device LBAand the storage system control logic is to receive an indicator relatedto the state of the respective target device LBA.

Example 9

This example includes the elements according to any one of examples 1through 6, wherein the request includes a range of target device LBAsand the storage system control logic is to receive indicators related tothe respective state of each target device LBA in the range of targetdevice LBAs.

Example 10

This example includes the elements according to any one of examples 1through 6, wherein the storage system control logic is further todetermine parity information based, at least in part, on the dataassociated with the mapped device LBA.

Example 11

According to this example there is provided a storage device. Thestorage device includes device control logic to determine a state of atarget device logical block address (LBA) in response to a request; ahost interface to provide a reply to the request, the reply including astate indicator related to the state of the target device LBA; a maptable including a plurality of device LBAs and respective stateindicators; and non-volatile memory (NVM) including data related to atleast one mapped LBA.

Example 12

This example includes the elements of example 11, wherein the devicecontrol logic is to unmap a device LBA in response to a receiving trimcommand (TRIM).

Example 13

This example includes the elements of example 11, wherein the devicecontrol logic is further to determine a respective state of each targetdevice LBA of a range of target device LBAs in response to the request.

Example 14

This example includes the elements of example 11, wherein the devicecontrol logic is further to determine a respective state of each deviceLBA of the plurality of device LBAs in response to the request.

Example 15

This example includes the elements of example 14, wherein the replyincludes at least a portion of the plurality of device LBAs and arespective state of each device LBA in the portion is mapped.

Example 16

This example includes the elements of example 11, wherein the statecorresponds to mapped or unmapped.

Example 17

This example includes the elements according to any one of examples 11through 16, wherein the host interface is compatible with at least oneof PCIe® (Peripheral Component Interconnect Express), SAS (SerialAttached SCSI (Small Computer System Interface)), ATA (AdvancedTechnology Attachment), SATA (Serial ATA) and/or NVMe (Non-VolatileMemory Host Controller Interface Express).

Example 18

This example includes the elements according to any one of examples 11through 16, wherein the NVM includes one or more of magnetoresistiverandom access memory (MRAM), phase change memory (PCM, PRAM), threedimensional crosspoint memory, resistive memory, ferroelectric memory(F-RAM, FeRAM), spin-transfer torque memory (STT), thermal assistedswitching memory (TAS), millipede memory, floating junction gate memory(FJG RAM), magnetic tunnel junction (MTJ) memory, electrochemical cells(ECM) memory, binary oxide filament cell memory, interfacial switchingmemory, battery-backed RAM and/or NAND flash memory.

Example 19

This example includes the elements according to any one of examples 11through 16, wherein the host interface is to couple the storage deviceto at least one of a storage system controller logic and/or a computingdevice.

Example 20

This example includes the elements according to any one of examples 11through 16, wherein the request is received from and the reply isprovided to storage system control logic.

Example 21

According to this example there is provided a method. The methodincludes identifying, by storage system control logic, at least onetarget storage device in response to detection of a failed storagedevice; requesting, by storage system control logic, a state of a targetdevice logical block address (LBA) from each of the at least one targetstorage device; reading, by storage system control logic, dataassociated with a mapped device LBA from each target storage device; andwriting, by storage system control logic, the data to at least onereplacement storage device.

Example 22

This example includes the elements of example 21 and further includesrequesting, by storage system control logic, a trim command (TRIM) froma computing device to be provided to each target storage device.

Example 23

This example includes the elements of example 21 and further includesidentifying, by storage system control logic, each target device LBA.

Example 24

This example includes the elements of example 21 and further includesrequesting, by storage system control logic, from each target storagedevice a respective state of each target device LBA of a range of targetdevice LBAs.

Example 25

This example includes the elements of example 21 and further includesrequesting, by storage system control logic, a listing of mapped deviceLBAs from each target storage device.

Example 26

This example includes the elements of example 21, wherein the statecorresponds to mapped or unmapped.

Example 27

This example includes the elements of example 21 and further includesrequesting, by storage system control logic, the state of each targetdevice LBA at least one of prior to and/or during a rebuild of thefailed storage device.

Example 28

This example includes the elements of example 21, wherein the requestincludes a respective target device LBA and further including receiving,by storage system control logic, an indicator related to the state ofthe respective target device LBA.

Example 29

This example includes the elements of example 21, wherein the requestincludes a range of target device LBAs and further including receiving,by storage system control logic, indicators related to the respectivestate of each target device LBA in the range of target device LBAs.

Example 30

This example includes the elements of example 21 and further includesdetermining, by storage system control logic, parity information based,at least in part, on the data associated with the mapped device LBA.

Example 31

According to this example there is provided a method. The methodincludes determining, by device control logic, a state of a targetdevice logical block address (LBA) in response to a request based, atleast in part, on a map table including a plurality of device LBAs andrespective state indicators, the map table related to a non-volatilememory (NVM) that includes data related to at least one mapped LBA; andproviding, by a host interface, a reply to the request, the replyincluding a state indicator related to the state of the target deviceLBA.

Example 32

This example includes the elements of example 31 and further includesunmapping, by the device control logic, a device LBA in response to areceiving trim command (TRIM).

Example 33

This example includes the elements of example 31 and further includesdetermining, by the device control logic, a respective state of eachtarget device LBA of a range of target device LBAs in response to therequest.

Example 34

This example includes the elements of example 31 and further includesdetermining, by the device control logic, a respective state of eachdevice LBA of the plurality of device LBAs in response to the request.

Example 35

This example includes the elements of example 34, wherein the replyincludes at least a portion of the plurality of device LBAs and arespective state of each device LBA in the portion is mapped.

Example 36

This example includes the elements of example 31, wherein the statecorresponds to mapped or unmapped.

Example 37

This example includes the elements of example 31, wherein the reply iscompatible with at least one of PCIe® (Peripheral Component InterconnectExpress), SAS (Serial Attached SCSI (Small Computer System Interface)),ATA (Advanced Technology Attachment), SATA (Serial ATA) and/or NVMe(Non-Volatile Memory Host Controller Interface Express).

Example 38

This example includes the elements of example 31, wherein the NVMincludes one or more of magnetoresistive random access memory (MRAM),phase change memory (PCM, PRAM), three dimensional crosspoint memory,resistive memory, ferroelectric memory (F-RAM, FeRAM), spin-transfertorque memory (STT), thermal assisted switching memory (TAS), millipedememory, floating junction gate memory (FJG RAM), magnetic tunneljunction (MTJ) memory, electrochemical cells (ECM) memory, binary oxidefilament cell memory, interfacial switching memory, battery-backed RAMand/or NAND flash memory.

Example 39

This example includes the elements of example 31 and further includescoupling, by the host interface, a storage device to at least one of astorage system controller logic and/or a computing device.

Example 40

This example includes the elements of example 31, wherein the request isreceived from and the reply is provided to storage system control logic.

Example 41

According to this example there is provided a computer-readable storagedevice having stored thereon instructions that when executed by one ormore processors result in the following operations including identifyingat least one target storage device in response to detection of a failedstorage device; requesting a state of a target device logical blockaddress (LBA) from each of the at least one target storage device;reading data associated with a mapped device LBA from each targetstorage device; and writing the data to at least one replacement storagedevice.

Example 42

This example includes the elements of example 41, wherein theinstructions that when executed by one or more processors results in thefollowing additional operations including requesting a trim command(TRIM) from a computing device to be provided to each target storagedevice.

Example 43

This example includes the elements of example 41, wherein theinstructions that when executed by one or more processors results in thefollowing additional operations including identifying each target deviceLBA.

Example 44

This example includes the elements of example 41, wherein theinstructions that when executed by one or more processors results in thefollowing additional operations including requesting from each targetstorage device a respective state of each target device LBA of a rangeof target device LBAs.

Example 45

This example includes the elements of example 41, wherein theinstructions that when executed by one or more processors results in thefollowing additional operations including requesting a listing of mappeddevice LBAs from each target storage device.

Example 46

This example includes the elements of example 41, wherein the statecorresponds to mapped or unmapped.

Example 47

This example includes the elements according to any one of examples 41through 46, wherein the instructions that when executed by one or moreprocessors results in the following additional operations includingrequesting the state of each target device LBA at least one of prior toand/or during a rebuild of the failed storage device.

Example 48

This example includes the elements according to any one of examples 41through 46, wherein the request includes a respective target device LBAand the instructions that when executed by one or more processorsresults in the following additional operations including receiving anindicator related to the state of the respective target device LBA.

Example 49

This example includes the elements according to any one of examples 41through 46, wherein the request includes a range of target device LBAsand the instructions that when executed by one or more processorsresults in the following additional operations including receivingindicators related to the respective state of each target device LBA inthe range of target device LBAs.

Example 50

This example includes the elements according to any one of examples 41through 46, wherein the instructions that when executed by one or moreprocessors results in the following additional operations includingdetermining parity information based, at least in part, on the dataassociated with the mapped device LBA.

Example 51

According to this example there is provided a computer-readable storagedevice having stored thereon instructions that when executed by one ormore processors result in the following operations including determininga state of a target device logical block address (LBA) in response to arequest, based, at least in part, on a map table including a pluralityof device LBAs and respective state indicators, the map table related toa non-volatile memory (NVM) that includes data related to at least onemapped LBA; and providing a reply to the request, the reply including astate indicator related to the state of the target device LBA.

Example 52

This example includes the elements of example 51, wherein theinstructions that when executed by one or more processors results in thefollowing additional operations including unmapping a device LBA inresponse to a receiving trim command (TRIM).

Example 53

This example includes the elements of example 51, wherein theinstructions that when executed by one or more processors results in thefollowing additional operations including determining a respective stateof each target device LBA of a range of target device LBAs in responseto the request.

Example 54

This example includes the elements of example 51, wherein theinstructions that when executed by one or more processors results in thefollowing additional operations including determining a respective stateof each device LBA of the plurality of device LBAs in response to therequest.

Example 55

This example includes the elements of example 54, wherein the replyincludes at least a portion of the plurality of device LBAs and arespective state of each device LBA in the portion is mapped.

Example 56

This example includes the elements of example 51, wherein the statecorresponds to mapped or unmapped.

Example 57

This example includes the elements according to any one of examples 51through 56, wherein the reply is compatible with at least one of PCIe®(Peripheral Component Interconnect Express), SAS (Serial Attached SCSI(Small Computer System Interface)), ATA (Advanced TechnologyAttachment), SATA (Serial ATA) and/or NVMe (Non-Volatile Memory HostController Interface Express).

Example 58

This example includes the elements according to any one of examples 51through 56, wherein the NVM includes one or more of magnetoresistiverandom access memory (MRAM), phase change memory (PCM, PRAM), threedimensional crosspoint memory, resistive memory, ferroelectric memory(F-RAM, FeRAM), spin-transfer torque memory (STT), thermal assistedswitching memory (TAS), millipede memory, floating junction gate memory(FJG RAM), magnetic tunnel junction (MTJ) memory, electrochemical cells(ECM) memory, binary oxide filament cell memory, interfacial switchingmemory, battery-backed RAM and/or NAND flash memory.

Example 59

This example includes the elements according to any one of examples 51through 56, wherein the instructions that when executed by one or moreprocessors results in the following additional operations includingcoupling a storage device to at least one of a storage system controllerlogic and/or a computing device.

Example 60

This example includes the elements according to any one of examples 51through 56, wherein the request is received from and the reply isprovided to storage system control logic.

Example 61

According to this example there is computer-readable storage devicehaving stored thereon instructions that when executed by one or moreprocessors result in the following operations including the methodaccording to any one of examples 21 to 30.

Example 62

According to this example there is computer-readable storage devicehaving stored thereon instructions that when executed by one or moreprocessors result in the following operations including the methodaccording to any one of examples 31 to 40.

Example 63

Another example of the present disclosure is a system including at leastone device arranged to perform the method of any one of examples 21 to30.

Example 64

Another example of the present disclosure is a system including at leastone device arranged to perform the method of any one of examples 31 to40.

Example 65

Another example of the present disclosure is a device including means toperform the method of any one of examples 21 to 30.

Example 66

Another example of the present disclosure is a device including means toperform the method of any one of examples 31 to 40.

The terms and expressions which have been employed herein are used asterms of description and not of limitation, and there is no intention,in the use of such terms and expressions, of excluding any equivalentsof the features shown and described (or portions thereof), and it isrecognized that various modifications are possible within the scope ofthe claims. Accordingly, the claims are intended to cover all suchequivalents.

Various features, aspects, and embodiments have been described herein.The features, aspects, and embodiments are susceptible to combinationwith one another as well as to variation and modification, as will beunderstood by those having skill in the art. The present disclosureshould, therefore, be considered to encompass such combinations,variations, and modifications.

What is claimed is:
 1. One or more non-transitory computer-readablestorage media having instructions stored thereon that when executed byat least one processor to cause the at least one processor of a firstcomputing device to perform operations, comprising: detect a failedstorage device in a plurality of storage devices; identify at least onetarget storage device of the plurality of storage devices; identifymapped logical block addresses (LBAs) of the at least one target storagedevice, the at least one target storage device to have associated mappedand unmapped LBAs; and responsive to the detection of the failed storagedevice: without reading data associated with the unmapped LBAs, readdata associated with the mapped LBAs from the at least one targetstorage device; and without writing data associated with the unmappedLBAs, write the data associated with the mapped LBAs to at least onereplacement storage device in the plurality of storage devices; whereinat least one of the unmapped LBAs is an LBA that has not been written toor has been subject to an UNMAP command and has not been written tosince the UNMAP command.
 2. The one or more non-transitorycomputer-readable storage media of claim 1, wherein at least one of themapped LBAs is an LBA that has been subject to a write operation and hasnot been subject to an UNMAP command since the write operation.
 3. Theone or more non-transitory computer-readable storage media of claim 1,wherein the UNMAP command is a TRIM command.
 4. The one or morenon-transitory computer-readable storage media of claim 1, wherein theUNMAP command is a Small Computer System Interface (SCSI) command. 5.The one or more non-transitory computer-readable storage media of claim1, wherein the at least one target storage device is at least one solidstate drive (SSD).
 6. The one or more non-transitory computer-readablestorage media of claim 1, wherein the instructions, when executed by theat least one processor of the first computing device, result inadditional operations comprising: request an UNMAP command from acomputing device to be provided to at least one target storage device.7. The one or more non-transitory computer-readable storage media ofclaim 1, wherein the instructions, when executed by the at least oneprocessor of the first computing device, result in additional operationscomprising: identify a state of at least one LBA in the at least onetarget storage device, said state being mapped or unmapped.
 8. The oneor more non-transitory computer-readable storage media of claim 7,wherein the instructions, when executed by the at least one processor ofthe first computing device, result in additional operations comprising:identify a state of at least one target storage device LBA in a range oftarget storage device LBAs, said state being mapped or unmapped.
 9. Theone or more non-transitory computer-readable storage media of claim 8,wherein the instructions, when executed by the at least one processor ofthe first computing device, result in additional operations comprising:cause device control logic of the at least one storage device to providea listing of mapped LBAs in at least one target storage device.
 10. Theone or more non-transitory computer-readable storage media of claim 9,wherein the device control logic is further to unmap a device LBA inresponse to an UNMAP command.
 11. A device, comprising: storage deviceinterface circuitry to communicate with a plurality of storage devices;and storage system control logic to: detect a failed storage device inthe plurality of storage devices; identify at least one target storagedevice of the plurality of storage devices; identify mapped logicalblock addresses (LBAs) of the at least one target storage device, the atleast one target storage device to have associated mapped and unmappedLBAs; and responsive to the detection of the failed storage device:without reading data associated with the unmapped LBAs, read dataassociated with the mapped LBAs from the at least one target storagedevice; and without writing data associated with the unmapped LBAs,write the data associated with the mapped LBAs to at least onereplacement storage device; wherein at least one of the unmapped LBAs isan LBA that has not been written to or has been subject to an UNMAPcommand and has not been written to since the UNMAP command.
 12. Thedevice of claim 11, wherein at least one of the mapped LBAs is an LBAthat has been subject to a write operation and has not been subject toan UNMAP command since the write operation.
 13. The device of claim 11,wherein the UNMAP command is a TRIM command.
 14. The device of claim 11,wherein the UNMAP command is a Small Computer System Interface (SCSI)command.
 15. The device of claim 11, wherein the at least one targetstorage device is at least one solid state drive (SSD).
 16. The deviceof claim 11, wherein the storage system control logic is further torequest an UNMAP command from a computing device to be provided to atleast one target storage device.
 17. The device of claim 11, wherein thestorage system control logic is further to identify a state of at leastone LBA in the at least one target storage device, said state beingmapped or unmapped.
 18. The device of claim 17, wherein the storagesystem control logic is further to identify a state of at least onetarget storage device LBA in a range of target storage device LBAs, saidstate being mapped or unmapped.
 19. The device of claim 18, wherein thestorage system control logic is further to cause device control logic ofat least one storage device to provide a listing of mapped LBAs in atleast one target storage device.
 20. The device of claim 19, wherein thestorage system control logic is further to unmap a device LBA inresponse to an UNMAP command.
 21. A system, comprising: a storagesystem, including: a plurality of storage devices; and storage systemcontrol logic to: detect a failed storage device in the plurality ofstorage devices; identify at least one target storage device of theplurality of storage devices; identify mapped logical block addresses(LBAs) of the at least one target storage device, the at least onetarget storage device to have associated mapped and unmapped LBAs; andresponsive to the detection of the failed storage device: withoutreading data associated with the unmapped LBAs, read data associatedwith the mapped LBAs from the at least one target storage device; andwithout writing data associated with the unmapped LBAs, write the dataassociated with the mapped LBAs to at least one replacement storagedevice; wherein at least one of the unmapped LBAs is an LBA that has notbeen written to or has been subject to an UNMAP command and has not beenwritten to since the UNMAP command; and a computing device, including: aprocessor; and chipset circuitry to couple the processor to the storagesystem.
 22. The system of claim 21, further comprising a display,wherein the chipset circuitry is further to couple the processor to thedisplay.
 23. The system of claim 21, wherein the storage system controllogic is further to identify a state of at least one LBA in the at leastone target storage device, said state being mapped or unmapped.
 24. Thesystem of claim 23, wherein the storage system control logic is furtherto identify a state of at least one target storage device LBA in a rangeof target storage device LBAs, said state being mapped or unmapped. 25.The system of claim 24, wherein the storage system control logic isfurther to cause device control logic of at least one storage device toprovide a listing of mapped LBAs in at least one target storage device.